Fuel Inj Control Unit Repair Made Easy
Your fuel injection control unit is a type of electronic control unit that manages your internal combustion engine's series of actuators. This, in turn, ensures optimal performance from your engine. The control unit reads values from a myriad of sensors within the bay of the engine then interprets the data with multidimensional performance maps known as lookup tables. With this data, it's able to adjust the engine actuators accordingly. With that said, here's how you go about fixing your fuel injection control unit so it continues to run slightly more efficient and leaner when all is said and done.
Difficulty Level: Moderate
What You'll Need
- Bungee cord
- Multimeter set
- Socket and wrench set
- Replacement fuel injection control unit
Step 1: Check if your batteries are still good and your alternator is healthy. Do the test only when the engine is cold. Remove the air filter restriction gauge, two hoses from the overflow jug, and cap to avoid coolant loss. Remove the two bolts holding the jug to the firewall.
Step 2: Pull the jug forward the fender then use a bungee cord to hold it. Atop the control unit is an oval plate held by T20 torx screws that you should remove. The number of screws will vary from car to car.
Step 3: Take your multimeter set on DC volts and connect the black ground lead to battery negative then connect the red lead to the screw closets to the driver's side fender. Warning: The control unit can cause lethal shock. Be careful when handling.
Step 4: Have an assistant work your ignition key. With the key on without engaging the start, measure the voltage. The voltage should be at 48 volts. Anything over 46 volts is okay. Also measure the voltage when cranking the engine. If the reading is above 46 volts, your control unit is okay.
Step 5: If your battery voltage is low, this can cause a false low fuel injection control unit reading. The reading should be no less than 45 volts and no more than a steady 48 volts. 25-35 volts means it can still run. Below 25 means it's not going to run.
Step 6: If your control unit is the seven-screw variety, then you should do the following. Get your multimeter set and connect it the black ground lead to battery negative and red lead to the screw in the line of 4, close to the engine centerline or from the driver's side fender.
Step 7: Measure the voltage with the key on rather than engaging the starter. It should read 46-48 volts. Next, measure the voltage while cranking the starter. If it stays above 46 volts, your fuel injector control unit is okay.
Step 8: Start your engine then measure the voltage. It should stay at no less than 45 volts all the way to 48 volts. You might have serious control unit problems if it's between only 25 to 35 volts. Below 25, and it won't run at all.
Step 9: When it comes to fuel injector control unit removal and replacement, you should remove the bolts holding the unit in place. Some of them are 8 millimeters while others are 10 millimeters.
Step 10: There are some cars with brackets that come along those bolts. Lift the unit up and remove the three harness plugs from its bottom. Get your new fuel injector control unit and install it in reverse order of how you removed the stock control unit.